Styling form error messages with CSS in Code Editor

Hi all,

I'm experimenting with adding CSS to the Code Editor to style my form, and I made some good progress. However I can't figure out how to style the error messages that appear when a field is required for example (see screenshot). They currently appear in Verdana 13px but I want them to appear in Arial 12px to match the font on my form. How do I do that?

Thanks for your help!

Joris